Study projects climate-related habitat losses for five western birds, gains for two

At least three-fourths of Pygmy Nuthatch’s range may disappear by 2099, a new report says. Photo by Laure Wilson Neish

Thanks to climate change, two western songbirds — Black-throated Sparrow and Gray Vireo — are projected to gain lots of breeding habitat by the end of this century.

Two others, however, may experience habitat losses that could move them close to extinction.

These are conclusions of new research published April 7, 2014, by scientists with the U.S. Geological Survey, the University of New Mexico, and Northern Arizona University.

The sparrow’s breeding range may increase by 34-47 percent between 2010 and 2099, and the vireo’s range is expected to grow even more: from 58 percent to 71 percent.

Five other species are forecast to experience slight to large losses in breeding habitat over the same period:

• Virginia’s Warbler: 1.5-7 percent projected decline

• Pinyon Jay: 25-31 percent projected decline

• Williamson’s Sapsucker: 73-78 percent projected decline

• Sage Thrasher (below): 78 percent projected decline

• Pygmy Nuthatch (above): 75-81 percent projected decline

“Not surprisingly, whether a species is projected to be a winner or a loser depends primarily on its natural history and habitat needs and requirements,” says USGS scientist Charles van Riper III, the lead author of the study.

The habitat losses for the sapsucker and nuthatch are “of a magnitude that could move these two species close to extinction within the next century,” the authors report. “Although both species currently have a relatively limited distribution, they can be locally common, and neither are presently considered candidates for prospective endangerment.”

To conduct the study, the researchers coupled existing global climate-change models with newly developed species-distribution models to estimate future losses and gains of seven southwestern bird species and five reptile species. The study area focused on the Sonoran Desert and Colorado Plateau ecosystems within Arizona, western New Mexico, Utah, southwestern Colorado, and southeastern California, where temperatures are projected to increase 6.3-7.2°F (3.5-4°C) in the next 60–90 years. Precipitation is projected to decline 5-20 percent.

“Changes of this magnitude may have profound effects on distribution and viability of many species,” noted Stephen T. Jackson, director of the Interior Department’s Southwest Climate Science Center. “Temperature matters a lot, biologically, in arid and semi-arid regions.”

In addition to publishing a 100-page report about their findings, the scientists posted range maps projecting the potential effects of climate change on the birds and reptiles they studied. Van Riper says the maps can help land managers and policy makers better prioritize conservation decisions. — Matt Mendenhall, Managing Editor